President Barack Obama has been meeting his senior national security advisers at the White House to discuss plans for possible military action against Syria.

The meeting, which included US Secretary of State John Kerry, was expected to be followed by the public release of a report on intelligence the US has gathered about last week's alleged chemical weapons attack in Syria.

Washington may proceed with military action against President Bashar al Assad's regime even without allied support, US officials have said.

But they stressed no final decision has been made on America's response to the Syrian government's suspected poison gas attack, which is said to have killed hundreds of people, including civilians.

Veto-holding members of the United Nations are at odds over a draft Security Council resolution that would authorise "all necessary force" in response to the alleged gas attack.

The UK's traditional role as America's most reliable military ally was called into question when David Cameron became the first British prime minister in history to be blocked by MPs over the prospect of military action.

A chastened-looking PM, struggling to make himself heard over calls of "resign" from the opposition benches, told them "I get it" as he abandoned hopes of joining any US strike on Syria.

Image:Mr Obama is under pressure to provide a legal rationale for military action

Speaking after the historic defeat, the White House said Mr Obama would decide on a response to chemical weapons use in Syria based on US interests, but that Washington would continue to consult with Britain.

British chancellor George Osborne acknowledged that the inability to commit British forces to any American-led operation against Assad would damage the special relationship between Westminster and Washington.

Video:'Major Embarrassment' For Cameron

He told BBC Radio 4's Today programme: "I think there will be a national soul-searching about our role in the world and whether Britain wants to play a big part in upholding the international system, be that big, open and trading nation that I like us to be, or whether we turn our back on that."

Sky's Foreign Affairs Editor Tim Marshall said the relationship between Britain and the US was "bruised but not broken". "I don't think there's a divorce on the cards, a bit of bickering perhaps," he added.

US Defence Secretary Chuck Hagel, speaking on a trip to the Philippines, said: "It is the goal of President Obama and our government ... whatever decision is taken, that it be an international collaboration and effort."

America is mulling whether to strike Syria without UN backing despite some of the more hawkish figures in the US cautioning against military action.

Former president, George W Bush, told Fox News Mr Obama had a "tough choice to make" but would not be drawn on what he should do.

He added: "I was not a fan of Mr Assad. He's an ally of Iran and has made mischief."

Former Defence Secretary Donald Rumsfeld, who helped spearhead US invasions in Iraq and Afghanistan, said: "There really hasn’t been any indication from the administration as to what our national interest is with respect to this particular situation."

He said, if anything, the US should be more concerned with Iran.

Video:Miliband Attacks 'Cavalier' Cameron

Earlier, top US officials spoke to key Democrat and Republican politicians for more than 90 minutes in a conference call to explain why they believe the Syrian regime was responsible for the suspected chemical attack.

They have been pressing Mr Obama to provide a legal rationale for military action, and to lay out a firm case linking Mr Assad's forces to the attack.

Tennessee Senator Bob Corker, a senior Republican on the Senate Foreign Relations Committee, said after the briefing that "strong evidence of the Assad regime's continued use of chemical warfare" merited a military response.

It remained to be seen whether any sceptics were swayed by the call, given the expectation that officials would hold back classified information to protect intelligence sources.

"The main thing was that they have no doubt that Assad's forces used chemical weapons," New York Rep Eliot Engel, the top Democrat on the House Foreign Affairs Committee, said after the briefing.

But he said officials did not provide much new evidence of that.

"They said they have (intercepted) some discussions and some indications from a high-level official," he said, and that they possess intelligence showing material being moved in advance of the attack.

France announced that its armed forces "have been put in position to respond" if President Francois Hollande decides on military action.

He does not need French parliamentary approval to launch military action that lasts less than four months.

Moscow and Beijing have both vetoed previous Western efforts to impose UN penalties on Syria.

China has also been keen to show it is not taking sides and has urged the Syrian government to talk to the opposition and meet demands for political change.

Mr Assad, who has denied using chemical weapons, vowed his country "will defend itself against any aggression".

Mr Obama has ruled out putting American forces on the ground in Syria or setting up a no-fly zone over the country.

He said any US response would be limited in scope and aimed solely at punishing Mr Assad for deploying deadly gas, not at regime change.

The most likely military option would be Tomahawk cruise missile strikes from four Navy destroyers in the eastern Mediterranean Sea.